Pedigree data on 447 person (322 white, 125 black) will be analyzed with a view to testing several previously reported major gene hypotheses: (1) the relative concentration of serum high density lipoprotein cholesterol and low density lipoprotein cholesterol being linked to either alpha-1- antitrypsin or haptoglobin; (2) a major gene for systolic blood pressure and an association/linkage between diastolic blood pressure and phosphoglucose dehydrogenase; and (3) associations of the A and B antigens with cholesterol levels, blood pressures, height and weight. A further 196 members in a single pedigree ar available for analysis of blood pressure. In addition, all available lipid and anthropometric traits will be screened for linkage (and hence possible monogenic mechanisms) to each of 31 polymorphic marker loci. The sample has a size that should be approximately adequate to replicate the major earlier findings, if they are in fact replicable.